This sentence makes the plot more dramatic because it drives Daedalus and Icarus to go to extremes to try to solve their conflict.  For example, because Daedalus and Icarus can’t leave the island by ship, Daedalus collects the feathers of local birds and shapes them with wax to form wings so he and his son can escape from their imprisonment.  This might have solved the conflict, but Icarus flies too high, which then causes the wax to melt and brings Icarus to his death in the waters off the island of Crete.  So, eventually,  the blockade of ships leads to Icarus’ death.
hope this helps ;)
